The invention relates to a secondary transformer unit for attachment to a vehicle with an electric drive having at least one secondary core and at least one secondary coil arranged on the secondary core, and to a vehicle with an electric drive.
Motor vehicles with an electric drive, such as hybrid cars and pure electric cars, which have traction batteries for supplying electric power to an electric motor, are known in the art. These conventional motor vehicles are equipped with a system for inductive energy transfer, which also allows a frequent recharging of the batteries with ease of use. This system works like a transformer and includes a primary transformer unit installed on the infrastructure side, for example on the rear wall of a garage, and a secondary transformer unit that is integrated at the front of the motor vehicle behind the front license plate.
The document DE 10 2009 023 409 A1 relates to a system for electric power transmission and forms the basis for the preamble of claim 1. This document discloses a secondary transformer unit or secondary transformer which is mounted at the bow or at the front of an electric vehicle and includes a U-shaped half transformer core and a coil winding wound thereon at an oblique angle. This secondary transformer unit is mounted at the front bumper of the electric vehicle, and the front license plate of the electric vehicle is mounted on the secondary transformer unit.
Since this conventional secondary transformer unit is mounted at the bow of the vehicle, it must be integrated in an area of the vehicle that has a high influence on the crash behavior in accidents involving pedestrians. In particular, the front of the vehicle becomes harder due to the additionally installed components, in particular the half-transformer core usually composed of magnetic steel sheets or ferrite; however, a well-defined and smooth vehicle front is necessary to minimize the risk of injury to pedestrians. Since the conventional secondary transformer unit is mounted at the front bumper behind the front license plate, less space remains available for deformation elements made of foam arranged between the bumper and the passenger compartment, requiring a reduction of their thickness, i.e. its extent in the direction of travel. This leads to a further increase of the hardness of the vehicle front.
DE 24 34 890 B1 describes an apparatus for connecting a charger arranged in a motor vehicle with an AC power grid or three-phase power grid. The apparatus is composed of a transformer divided into two parts, wherein the two parts each have a core on which the respective primary and secondary windings are arranged. The transformer part connected to an AC power grid and having the primary windings is arranged in a charging board of a parking space, whereas the transformer part connected to the secondary windings is located in a bumper of the motor vehicle. The transformer parts are provided with a plastic cover for corrosion protection.
DE 37 18 676 A1 discloses a molded article made of composite material, in particular of a hybrid material of fiber reinforced plastic and metal with a film-like or layer-like or spongy or network-like core which is embedded in plastic. The reinforcing fibers may be made of aramide, carbon and/or glass.